Each year 550,000 new people are diagnosed with heart failure (HF). In the year 2006, 1.1 million hospital discharges were reported, and the estimated direct and indirect cost of HF in the United States is approximately $39.2 billion for 2010. There is evidence that exercise can help patients with HF improve their functional capacity and quality of life as well as being associated with decreased mortality and hospitalization. Exercise has been shown to be efficacious and safe for people diagnosed in all New York Heart Association Classifications (I - IV). However, a low percentage of HF patients initiate and/or maintain exercise behavior as HF patients have reported more difficulty with exercising compared to other prescribed HF management activities. Understanding the factors that enhance or hinder HF patients'ability to begin and maintain exercise behavior is important for development of interventions to assist them in improving their functional capacity and quality of life. Self-efficacy, outcome expectancy, and social support are all concepts from Bandura's social- cognitive theory. These specific concepts of social cognitive theory have been shown to be significant predictors for exercise initiation and maintenance in some older adult populations. There have been several models tested to explain exercise behavior utilizing components of social cognitive theory in general for older adults and patients in cardiac rehabilitation. These models are not identical to each other and to date no model of exercise behavior using specific concepts of social cognitive theory has been tested in the HF population. The purpose of this study is to understand if factors affecting exercise behavior in other populations explain exercise behavior in HF patients. The specific aim of this research is to identify and determine the strength of theory-driven factors associated with exercise behavior in HF patients. A greater understanding of factors associated with increased exercise behavior in HF patients will lead to the development of more effective interventions to promote exercise behavior that improves overall health status and decreases hospitalizations. PUBLIC HEALTH RELEVANCE: Heart failure (HF) is a disease that burdens many people in our society by decreasing their functional ability and quality of life. Exercise has been shown to help people with HF increase what they are able to do during the day which improves their quality of life. However, HF patients have reported that exercise is more difficult to perform than other prescribed HF management behaviors (e.g. eating a low sodium diet or regularly weighing themselves). In order to design interventions to help people with HF to increase exercise behavior, we need to understand what factors are strongly associated with exercise in this population.